I mean, Easter is the main show for Christians... And... I suppose the real question is... HOW should Christians celebrate Christmas...
To what extent, if at all, should they join in with the pagan revelries, and with the worship of various plants and trees?
What pagan revelries or worship of plants and trees?
The Feast of the Holy Nativity of the Lord Jesus, better known as Christmas or Christ's Mass, i.e. "the Feast of Christ" has been part of the Christian liturgical calendar since antiquity.
Since at least as early as the early 3rd century Christians have been discussing things such as on what calendar day was Jesus' death? What day was He born? Etc. From pretty early on we see a pretty common consensus among Christians that Jesus had been crucified on a March 25th. Christians then speculated that if Christ had died on a March 25th, then maybe He was also born, or perhaps He was conceived on March 25th. The rationale for this was that since Jesus, being perfect, would have lived a perfect number of years--thus dying on the same day He was either conceived or born.
At the time Christians had already been celebrating the Epiphany, the second oldest Christian liturgical season, the oldest being the Paschal (Easter) Season. The Epiphany, from the Greek word meaning "manifestation" was a kind of general celebration of Christ's manifestation of Himself--in some places the emphasis was on His baptism in the Jordan river by John the Baptist, on other places it was associated with His Incarnation/birth. Epiphany begins on the Feast of Holy Epiphany, January 6th. In the Armenian Church, even to this day, Christmas is celebrated on January 6th (where the Nativity and Epiphany are co-celebrated as one Feast).
December 25th became associated with Christ's Nativity by a simple calculation of nine months from March 25th. That is, those who reckoned Christ's conception on March 25th simply added nine months to get December 25th.
Church services dedicated to Christ's Nativity occurring on December 25th had to have already become quite common, at least in some church jurisdictions, by the mid-4th century as
we have a written record from the year 354 AD in which December 25th is recorded on a calendar as the Feast of Christ's Nativity.
By the 6th century the celebration of Christ's Nativity on December 25th had become so widespread, that it was made official in most church jurisdictions. Though, as noted already, the Armenian Church continues to celebrate Christmas on January 6th, rather than December 25th.
Pagan connections with Christmas are, at best, weak and spurious conjecture. It's more of a popular myth than anything taken serious in any academic setting.
As for modern, western ways in which Christmas is celebrated, that is the sort of external cultural motifs; those things are really more a pastiche of accumulated cultural customs. Some having explicitly Christian origins, and others largely as cultural winter miscellany. Some of those fluffy cultural artifacts probably did have some origins among pagans who converted to Christianity, but there simply isn't anything innately "pagan" about them. An end of the harvest celebration with eating, drinking, fire, song, dance is something we find in a lot of cultures, and which absolutely were things pagan people did--but that doesn't mean that the American civil holiday of Thanksgiving (as an example) is full of "pagan revelry". Because there's nothing wrong with eating, drinking, fire, song, dance, and communities enjoying life together in harmless ways. By the same token, there's nothing harmful about the cute little tradition of kissing under the mistletoe. Nobody worships mistletoe, and it's not some intrinsic part of Christmas. It's just cultural fluff, and it's fine.
It's okay to be a Christian to also have fun.
-CryptoLutheran
